1、Chapter 2 Valuing The Environment:Concepts1.IntroductionMain contents:Develop the general conceptual framework used in economics to approach environmental problems.Examining the relationship between human actions,as manifested through the economic system,and the environmental consequences of those a
2、ctions.Establish criteria for judging the desirability of the outcomes of this relationship.2.The Human Environmental Relationship2.1 The Environment as an Asset2.2 The Economic Approach2.1 The Environment as an AssetIn economics the environment is viewed as a composite asset（复合资产）（复合资产）that provide
3、s a variety of services.Provides the economy with raw materials and energyAlso provides services directly to consumers,such as air,water,amenities,etc.2.1 The Environment as an AssetIf the environment is defined broadly enough,the relationship between the environment and the economic system can be c
4、onsidered a closed system.A closed system（封闭系统）（封闭系统）is one in which no inputs are received from outside the system and no outputs are transferred outside the system.An open system（开放系统）（开放系统）is one in which the system imports or exports matter or energy.2.1 The Environment as an AssetThe first law
5、of thermodynamics（热力学（热力学第一定律）第一定律）The law states that energy and matter cannot be created or destroyed in a closed system.The law implies that the mass of materials flowing into the economic system from the environment has to either accumulate in the economic system or return to the environment as
6、waste.2.1 The Environment as an AssetThe second law of thermodynamics（热力（热力学第二定律）学第二定律）The law states that entropy（熵）increases.Applied to energy processes,this law implies that no conversion from one form of energy to another is completely efficient and that the consumption of energy is an irreversi
7、ble process.Also implies that in the absence of new energy input,any closed system must eventually use up its energy.2.2 The Economic ApproachTwo different types of economic analysis can be applied to increase our understanding of the relationship between the economic system and the environment.Posi
8、tive economics（实证经济学）（实证经济学）attempts to describe what is,what was,or what will beNormative economics（规范经济学）（规范经济学）deals with what ought to be.3.Normative Criteria for Decision-MakingEconomists suggest that actions have both benefits（收益）and costs（成本）.If the benefits exceed the costs,then the action i
9、s desirable.If the costs exceed the benefits,then the action is not desirable.If BC,then support the action,otherwise oppose the actionIf B/C1,support the action otherwise,oppose the action3.Normative Criteria for Decision-MakingHow to measure benefits and costs?3.Normative Criteria for Decision-Mak
10、ingBenefits（收益）can be derived from the demand curve for the good or service provided by the action.Demand curves（需求曲线）（需求曲线）measures the amount of a particular good people would be willing to purchase at various prices.Figure 2.2Figure 2.33.Normative Criteria for Decision-MakingMeasuring total costs
11、（总成本）（总成本）on the same set of axes involves logic similar to measuring total benefits.All costs should be measured as opportunity costs（机会成本）（机会成本）.It is important to stress that environmental services have costs even though they are produced without any human input.Total cost is simply the sum of th
12、e marginal costs（边际成本）（边际成本）.Figure 2.43.Normative Criteria for Decision-MakingSince net benefit（净收益）（净收益）is defined as the excess of benefits over costs,it follows that net benefit is equal to that portion of the area under the demand curve which lies above the supply curve.Figure 2.53.Normative Cr
13、iteria for Decision-MakingThe analysis we have covered so far is very useful for thinking about actions where time is not an important factor.How can we make choices when the benefits and costs may occur at different points in time?In order to incorporate timing,the decision rule must provide a way
14、to compare the net benefit received in one period with the net benefit received in another.The concept that allows this comparison is called present value（现值）（现值）.3.Normative Criteria for Decision-MakingThe present value of a one-time net benefits received n years from now is The present value of a
15、stream of net benefits B0,Bn received over a period of n years is computed as 3.Normative Criteria for Decision-MakingIt is now possible to show how this analysis can be used to evaluate actions.First calculate the present value（现值）of net benefits（净收益）from the actionIf the present value is greater t
16、han zero,the action should be supported.Otherwise it should not.4.Finding the Optimal OutcomeThree steps proceeded by normative analysis:First we will identify an optimal（最优的）outcome.Second we will attempt to discern the extent to which our institutions produce optimal outcomes and,where divergences
17、 occur between actual and optimal outcomes,to attempt to uncover the behavioral sources of the problems.Finally designing appropriate policy solutions.Examples:Consider the rising number of depleted ocean fisheries.Depleted fisheries not only jeopardize oceanic biodiversity,but also pose a threat to
18、 both the individuals who make their living from the sea and the communities that have depended on fishing to support their local economies.How would an economist attempt to understand and to resolve this problem?Example:The first step would involve defining the optimal stock（最优存量）or the optimal rat
19、e of harvest（最优捕捞率）of the fishery.The second step would compare this level with the actual stock and harvest levels.The third step would reach the solutions.4.1 Static EfficiencyThe chief normative economic criterion for choosing among various allocations occurring at the same point in time is calle
20、d static efficiency（静态效率）（静态效率）.An allocation of resources is said to satisfy the static efficiency criterion if the net benefit from the use of those resources is maximized（最大化）by that allocation.4.1 Static EfficiencyFirst Equimarginal Principle(the“Efficiency Equimarginal Principle”)（第一等边际原理）:Net
21、benefits are maximized when the marginal benefits from an allocation equal the marginal costs.Pareto Optimality（帕累托最优）（帕累托最优）:Allocations are said to be Pareto optimal if no other feasible allocation could benefit some people without any deleterious effects on at least one other person.4.2 Dynamic E
22、fficiencyThe traditional criterion used to find an optimal allocation when time is involved is called dynamic efficiency（动态效率）（动态效率）.An allocation of resources across n time periods satisfies the dynamic efficiency criterion if it maximizes the present value of net benefits that could be received fr
23、om all the possible ways of allocation those resources over the n periods.5.Applying the conceptsPollution controlPreservation versus development二氧化碳减排的效益评估 二氧化碳减排的收益？碳社会成本：指二氧化碳排放的少量增长导致的经济损失现值（如，海平面的上升、洪水、农业产量的变化、及变化了的生态服务）的边际增长。Further reading:A 迈克里 弗里曼，环境与资源价值评估理论与方法，中国人民大学出版社，2002Objectives&Req
24、uirements:Understand the human environmental relationshipGrasp the normative criteria for decision-making and optimal outcomeUnderstand the meaning of“static efficiency”and“dynamic efficiency”Problems:One convenient way to express the willingness-to-pay relationship between price and quantity is to
25、use the inverse demand function.In an inverse demand function,the price consumers are willing to pay is expressed as a function of the quantity available for sale.Suppose the inverse demand function or a product is P=80-q,and the marginal cost of producing it is MC=1q,where P is the price of the product and q is the quantity demanded and/or supplied.How much would be supplied in a static efficient allocation?What would be the magnitude of the net benefits?
